1. Field of the Invention
The present invention relates to a recording apparatus for recording on a recording medium conveyed by a conveying mechanism portion using recording means.
2. Related Background Art
As output apparatuses of various information processing apparatuses including personal computers, recording apparatuses have been used for recording on a recording medium using recording means based on recording information, such as printers, image forming apparatuses, facsimiles, or copiers. The recording apparatuses are classified into thermal transfer recording apparatuses, inkjet recording apparatuses, laser recording apparatuses, wire dot recording apparatuses, or the like according to the kinds of the recording apparatuses. The recording apparatuses are adapted for recording on a recording medium conveyed by a conveying mechanism portion, and classified into apparatuses of a serial type for recording while performing main scanning of a recording medium using recording means and apparatuses of a line type for recording by conveyance (sub scanning) of a recording medium, according to the recording type.
In the conveying mechanism portion in the recording apparatus, higher conveyance accuracy in conveying the recording medium and a quieter conveying operation have been required. In recent years, images recorded on a recording medium have been including pictures rather than text only, which has been requiring higher and higher conveyance accuracy of the conveying mechanism portion. Such a technique for improving conveyance accuracy is disclosed in, for example, U.S. Pat. No. 6,685,370.
The conveying mechanism portion in the conventional recording apparatus has the following problems. First, in order to reduce conveyance resolution of the conveying mechanism portion to increase resolution, either a method of reducing a diameter of a conveying roller or a method of providing finer resolution of a code wheel provided coaxially with the conveying roller needs to be used. However, the method of reducing the diameter of the conveying roller makes it difficult to ensure conveyance accuracy, and thus either a method of increasing a diameter of the code wheel to increase the resolution or a method of increasing resolution of an encoder only can be used, both of which increase costs. Increasing the diameter of the code wheel increases the size of the apparatus.
Second, reducing the conveyance resolution to increase the resolution may affects a reduction ratio from a conveying motor to the conveying roller to prevent an optimum RPM of the motor or optimum motor torque from being chosen in selecting the conveying motor. Further, variations of conveyance distances or conveyance accuracy differ among conveyance of the recording medium by the conveying roller only (recording on a leading end of the recording medium), conveyance of the recording medium by the conveying roller and a paper expelling roller (recording on the center of the recording medium), and conveyance of the recording medium by the paper expelling roller only (recording on a rear end of the recording medium).